C#操作註冊表建立檔案關聯

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;

namespace Mydoc
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        public static void SaveReg(string p_Filename, string p_FileTypeName)
        {
            RegistryKey _RegKey = Registry.ClassesRoot.OpenSubKey("", true);              //開啟註冊表

            RegistryKey _VRPkey = _RegKey.OpenSubKey(p_FileTypeName);
            if (_VRPkey != null) _RegKey.DeleteSubKey(p_FileTypeName, true);
            _RegKey.CreateSubKey(p_FileTypeName);
            _VRPkey = _RegKey.OpenSubKey(p_FileTypeName, true);
            _VRPkey.SetValue("", "Exec");

            _VRPkey = _RegKey.OpenSubKey("Exec", true);
            if (_VRPkey != null) _RegKey.DeleteSubKeyTree("Exec");         //如果等於空 就刪除註冊表DSKJIVR

            _RegKey.CreateSubKey("Exec");
            _VRPkey = _RegKey.OpenSubKey("Exec", true);
            _VRPkey.CreateSubKey("shell");
            _VRPkey = _VRPkey.OpenSubKey("shell", true);                      //寫入必須路徑
            _VRPkey.CreateSubKey("open");
            _VRPkey = _VRPkey.OpenSubKey("open", true);
            _VRPkey.CreateSubKey("command");
            _VRPkey = _VRPkey.OpenSubKey("command", true);
            string _PathString = "/"" + p_Filename + "/" /"%1/"";
            _VRPkey.SetValue("", _PathString);                                    //寫入資料

        }
        public static void DelReg(string p_FileTypeName)
        {
            RegistryKey _Regkey = Registry.ClassesRoot.OpenSubKey("", true);

            RegistryKey _VRPkey = _Regkey.OpenSubKey(p_FileTypeName);
            if (_VRPkey != null) _Regkey.DeleteSubKey(p_FileTypeName, true);
            if (_VRPkey != null) _Regkey.DeleteSubKeyTree("Exec");

        }

 

        private void Form1_Load(object sender, EventArgs e)
        {

            SaveReg(Application.ExecutablePath,".task");
            string[] argv=Environment.GetCommandLineArgs();
            if (argv.GetLength(0) == 2)
            {
                MessageBox.Show(argv[1]);
            }
        }
    }
}